Ferrera Beta-thalassemic patients characteristically do not synthesize Beta-globin molecules. We were recently able to induce Beta-globin synthesis in Ferrara thalassemic ribosomes by cell-free incubations in which the thalassemic supernatant was replaced with ribosome- and mRNA-free cytoplasm from normal red blood cells. Thalassemic ribosomes contain therefore normal Beta-globin mRNA, the translation of which can be obtained only after addition of a specific factor present in normal red blood cells and lacking, or not functioning, in thalassemic erythrocytes. The main finding obtained in the past year has been the observation that in 55 Beta degrees- thalassemic subjects the transfusion of normal blood is followed by the appearance of Beta-globin synthesis and reduction of the excess of alpha-synthesis to normal values. A careful analysis of the phenomenon revealed its occurrence within the thalassemic erythroid cells. The newly synthesized Beta-globin molecules produced after blood transfusion have been purified and characterized with several techniques, including chromatographic separation of their tryptic peptides (Nature, in press). The "in vivo" induction of Beta-globin synthesis after blood transfusion suggests that the specific inducer of Beta-globin synthesis eventually isolated from normal red blood cells is able to cross the thalassemic red cell wall, thus replacing the absent or not functioning thalassemic factor in inducing Beta-globin mRNA translation. This observation opens the practical possibility of the use for therapeutic purposes of the inducer of Beta-globin synthesis.